Metal seal weld-on connector for conductor casing
The present invention relates to an improved weld-on connector to achieve 5 high tensile strength, burst pressure and collapse pressure. The present invention relates to the metal seal weld-on connector for conductor casing with different types of sealings and several other designed features to provide an improved strength for the threaded connection.
1 . An improved weld-on connector ( 1 ) for conductor casing comprising:
a circular box member ( 2 ) having internal threads at tapered inner surface; and
a circular pin member ( 3 ) having matching external threads at tapered outer surface fastened on the internal threads of the box member ( 2 );
wherein,
said weld-on connector ( 1 ) provides a first sealing comprising metal-to-metal seal over a tapered surface near a free end ( 8 ) of the pin member ( 3 ) to protect the internal threads and the external threads of the connector assembly ( 1 ) from fluid flowing inside the pin member ( 3 );
said weld-on connector ( 1 ) provides a second sealing provided by an O-ring ( 4 ) located in a groove ( 5 ) in the pin member ( 3 ) to protect the internal threads and the external threads from fluids flowing outside the connector assembly ( 1 );
said weld-on connector ( 1 ) provides a face-to-face sealing at two places in connector ( 1 ) wherein a face-to-face sealing ( 12 b ) is effected by providing a matching seat ( 14 ) in the box member ( 2 ) that mates with a protrusion ( 13 ) in the pin member ( 3 ) and other face-to-face sealing is effected over load flank surface ( 12 a ) of the internal threads and the external threads of connector ( 1 ); and
said internal threads and the external threads are pre-loaded for fatigue and are multi-start to achieve full make up in 1 to 2 rotations.
2 . The improved weld-on connector ( 1 ) for conductor casing as claimed in claim 1 , wherein, said threads of box member ( 2 ) and pin member ( 3 ) are modified buttress threads with a stab flank angle of 20-30 degrees and said connector has a deep stabbing ( 6 ) to eliminate cross threading.
3 . The improved weld-on connector ( 1 ) for conductor casing as claimed in claim 2 , wherein, said threads have load flank surface ( 12 a ) and stab flank surface ( 17 ) of box member ( 2 ) and stab flank surface ( 20 ) of pin member ( 3 ) with a desired-clearance between them.
4 . The improved weld-on connector ( 1 ) for conductor casing as claimed in claim 1 , wherein, said first metal-to-metal sealing is due to radial interference between the outer surface of the pin member ( 3 ) and the inner surface of the box member ( 2 ).
5 . The improved weld-on connector ( 1 ) for conductor casing as claimed in claim 1 , wherein, the outer surface of the pin member ( 3 ) over a length ‘a’ from the free end ( 8 ) of pin member ( 3 ) is straight and further has a surface profile having multi-radii taper.
6 . The improved weld-on connector ( 1 ) for conductor casing as claimed in claim 1 , wherein, the weld on connector ( 1 ) is carried out for different conductor casing sizes ranging from 18.625″ to 36″.
7 . The improved weld-on connector ( 1 ) for conductor casing as claimed in claim 1 , wherein, the protrusion ( 13 ) of the pin member ( 3 ) seated in the box member ( 2 ) ensures that connector ( 1 ) does not over-torque and prevents damage to the threads due to breaking of metal and prevents galling.
8 . The improved weld-on connector ( 1 ) for conductor casing as claimed in claim 1 , wherein, the protrusion ( 13 ) has chamfered corners near its free end ( 8 ) and the matching seat ( 14 ) in the box member ( 2 ) has smooth curves to ensure no localized over stress points.
9 . The improved weld-on connector ( 1 ) for conductor casing as claimed in claim 1 , wherein, the protrusion ( 13 ) of the pin member makes an angle A with a plane perpendicular to the axis of the connector ( 1 ) is and the value of A lies in the range 10 to 20 degrees.